1. Field of the Invention
This invention relates to an auto-lock slider for use in an ordinary type slide fastener, and more particularly to an auto-lock slide fastener slider in which locking function is performed by pivotal movement of a pull tab, without using a spring.
2. Description of the Related Art
FIG. 7 of the accompanying drawings shows a conventional auto-lock slide fastener slider as disclosed in Japanese Utility Model Publication No. Sho 45-2165. In this conventional slider, a locking leaf spring 102 having a U-shaped locking projection 109 is floatably seated in a central arcuate recess 110 of the upper wing 115 with one end fixed in a recess 133 near a front end of the central recess 110 with the U-shaped locking projection 119 being able to be fitted in the locking-projection-insertion hole 111 provided in a bottom of the recess 110. A pull tab 103 has at one end an axle rotatably supported by a pair of pull-tab-attachment lugs 114 standing on the upper wing 105 at opposite sides of the central recess 110 and a cam 122 on the axle. In response to pivotal movement of the pull tab 103 from an upright posture to a horizontal posture, the cam 122 resiliently bends the leaf spring 102 so as to insert the locking projection 119 through the locking-projection-insertion hole 111 communicating with the recess 110.
FIG. 8 shows another conventional auto-lock slide fastener slider as disclosed in Japanese Utility Model Publication No. Sho 51-523766. In this conventional slider, a locking plate 102 having on its lower surface a locking pawl 119 is loosely received in a recess 110 of the upper wing 105 for pivotal movement about a rear end of the recess 110 and also for sliding movement in longitudinal direction, the cutout having a varying depth progressively increasing from its rear end, which is off the fulcrum 121 of a pull tab 103 to the rear side, toward its front end. The locking plate 102 has on its upper surface a central projection 134 having a perpendicular front surface and a convex rear surface. The pull tab 103 has in its front end portion at a position off an axle 121 a cutaway 120 complementary in shape to the central projection 134 of the locking plate 102 so that the central projection 134 can be fitted in the cutaway 120 when the pull tab 103 assumes a horizontal posture. Also the pull tab 103 has a cam 122 being forward of the cutaway 120 point-symmetric in shape with and contiguous with the central projection 134.
According to the auto-lock slider of FIG. 7, when it assumes a horizontal posture to lock the slider, the pull tab 103 tends to be pushed upwardly partly because the U-shaped locking projection 119 is raised by the fastener elements and partly since the locking leaf spring 102 slides to the rear side by its own restoration, thus resulting in a non-stable locking operation. Further, since the locking projection 119 of the leaf spring 102 is merely curved in a U shape, it tends to deform so that a precise locking operation cannot be expected.
According to the auto-lock slider of FIG. 8, since, in response to pivotal movement of the pull tab 103, the locking plate 102 is pivotally moved in the vertical direction and is slid in the longitudinal direction, it is necessary to press a grip portion of the pull tab against the slider body in order to insert the locking pawl 119 between adjacent fastener elements, thus resulting in a very meticulous and non-smooth locking operation. Further, since, for sliding the slider, it is required to pivotally move and slide the locking plate 102 by pivotally moving the pull tab 103 to an upright posture, a smooth sliding operation cannot be expected as the locking plate 102 is held non-stably.